<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt"><div><span>Hi!</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><span>About simplification (no clustering), </span><span style="background-color: transparent; font-size: 12pt;">I think that the </span><span style="background-color: transparent;">If we discard points based on the distance to the last fetched and rendered point (</span><span style="background-color:
transparent;">https://github.com/qgis/QGIS/blob/master/src/core/qgsfeatureiterator.cpp#L36) it will be very effective to render big dense points layers. I have a GIS application using this technique and it draws LAS files (> 30mb) "fast".</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><span style="background-color: transparent;"><br></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><span style="background-color: transparent;">I would like write a "point simplifier" in QGIS to validate results.</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande',
sans-serif; background-color: transparent; font-style: normal;"><span style="background-color: transparent;">Do you agree ?</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><span style="background-color: transparent;"><br></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><span style="background-color: transparent;">Alvaro</span></div><div><br></div><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; margin-top: 5px; padding-left: 5px;"> <div style="font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 12pt;"> <div style="font-family: HelveticaNeue, 'Helvetica Neue',
Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 12pt;"> <div dir="ltr"> <hr size="1"> <font size="2" face="Arial"> <b><span style="font-weight:bold;">De:</span></b> Tim Sutton <lists@linfiniti.com><br> <b><span style="font-weight: bold;">Para:</span></b> Martin Dobias <wonder.sk@gmail.com> <br><b><span style="font-weight: bold;">CC:</span></b> qgis-developer <qgis-developer@lists.osgeo.org>; "tech@wildintellect.com" <tech@wildintellect.com> <br> <b><span style="font-weight: bold;">Enviado:</span></b> Jueves 23 de enero de 2014 23:16<br> <b><span style="font-weight: bold;">Asunto:</span></b> Re: [Qgis-developer] On the fly simplication of point layers<br> </font> </div> <div class="y_msg_container"><br><div id="yiv8548484203"><div><div dir="ltr">Hi<div class="yiv8548484203gmail_extra"><br clear="none"><br clear="none"><div class="yiv8548484203gmail_quote">On Wed, Jan 22, 2014 at 2:47 PM, Tim Sutton <span
dir="ltr"><<a rel="nofollow" shape="rect" ymailto="mailto:lists@linfiniti.com" target="_blank" href="mailto:lists@linfiniti.com">lists@linfiniti.com</a>></span> wrote:<br clear="none">
<blockquote class="yiv8548484203gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div dir="ltr">Hi<div class="yiv8548484203gmail_extra"><br clear="none"><br clear="none"><div class="yiv8548484203gmail_quote"><div><div class="yiv8548484203h5">On Wed, Jan 22, 2014 at 1:23 PM, Martin Dobias <span dir="ltr"><<a rel="nofollow" shape="rect" ymailto="mailto:wonder.sk@gmail.com" target="_blank" href="mailto:wonder.sk@gmail.com">wonder.sk@gmail.com</a>></span> wrote:<br clear="none">
<blockquote class="yiv8548484203gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div>On Wed, Jan 22, 2014 at 4:33 PM, Tim Sutton <<a rel="nofollow" shape="rect" ymailto="mailto:lists@linfiniti.com" target="_blank" href="mailto:lists@linfiniti.com">lists@linfiniti.com</a>> wrote:<br clear="none">
>><br clear="none">
>> Actually the point displacement renderer already does clustering,<br clear="none">
>> though it lacks more options to customize how the clustered symbol<br clear="none">
>> would look like.<br clear="none">
>><br clear="none">
><br clear="none">
> Doesnt it do the reverse? i.e. when more than one point falls in the same<br clear="none">
> place, it shifts them aside so they are all visible. If it can be made to<br clear="none">
> produce a scaled symbol based on the number of underlying points that would<br clear="none">
> be cool.That would also be a good time to change its name to 'Custer or<br clear="none">
> displace' or something.<br clear="none">
<br clear="none">
</div>I think that was what the renderer did originally, but nowadays it<br clear="none">
also groups points within configured distance. Unfortunately it always<br clear="none">
tries to draw a circle around the clustered point with original<br clear="none">
symbols. If we introduced few rendering options, it would be more<br clear="none">
useful:<br clear="none">
- draw just the clustered symbol for the whole group<br clear="none">
- scale the clustered symbol depending on the number of points inside<br clear="none">
<br clear="none"></blockquote><div><br clear="none"></div></div></div><div>Yeah that should do it!</div><div><br clear="none"></div></div></div></div></blockquote><div><br clear="none"></div><div>I tested with a large point dataset (geonames ~3.5 million records). Basically enabling the point displacement renderer on that layer kills (or takes so long I killed it) QGIS. Since the essence of clustering is to speed up rendering times and reduce visual clutter, I suspect simple tweaks to the renderer would not be enough.</div>
<div><br clear="none"></div><div>Regards</div><div><br clear="none"></div><div>Tim</div><div><br clear="none"></div><div> </div><blockquote class="yiv8548484203gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div dir="ltr"><div class="yiv8548484203gmail_extra">
<div class="yiv8548484203gmail_quote"><div></div><div>Regards</div><div><br clear="none"></div><div>Tim</div><div> </div><blockquote class="yiv8548484203gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Cheers<br clear="none">
<span><font color="#888888">Martin<br clear="none">
</font></span></blockquote></div><div class="yiv8548484203im"><br clear="none"><br clear="all"><div><br clear="none"></div>-- <br clear="none"><div dir="ltr">Tim Sutton - QGIS Project Steering Committee Member<br clear="none">==============================================<br clear="none">Please do not email me off-list with technical<br clear="none">
support questions. Using the lists will gain<br clear="none">more exposure for your issues and the knowledge<br clear="none">surrounding your issue will be shared with all.<br clear="none"><br clear="none">Irc: timlinux on #qgis at <a rel="nofollow" shape="rect" target="_blank" href="http://freenode.net/">freenode.net</a><div class="yiv8548484203yqt4500995229" id="yiv8548484203yqtfd17178"><br clear="none">
==============================================</div></div><div class="yiv8548484203yqt4500995229" id="yiv8548484203yqtfd65879">
</div></div></div></div><div class="yiv8548484203yqt4500995229" id="yiv8548484203yqtfd95624">
</div></blockquote></div><div class="yiv8548484203yqt4500995229" id="yiv8548484203yqtfd45985"><br clear="none"><br clear="all"><div><br clear="none"></div>-- <br clear="none"><div dir="ltr">Tim Sutton - QGIS Project Steering Committee Member<br clear="none">==============================================<br clear="none">Please do not email me off-list with technical<br clear="none">
support questions. Using the lists will gain<br clear="none">more exposure for your issues and the knowledge<br clear="none">surrounding your issue will be shared with all.<br clear="none"><br clear="none">Irc: timlinux on #qgis at <a rel="nofollow" shape="rect" target="_blank" href="http://freenode.net/">freenode.net</a><br clear="none">
==============================================</div>
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